ADENOVIRUSES. We will focus on the continued analysis of the viral-coded early proteins. Purification of these proteins will continue and purified proteins will be used in biochemical studies designed to elucidate functions of these proteins. Partial amino acid sequenceing data will focus on structural analysis of the 5'-termini of adenovirus early mRNAs, with the goals of identifying signals that regulate transcription or processing of mRNA. Molecular genetics projects will concentrate on the development of early mutants and on the restructuring in vitro of the adenovirus genome. RETROVIRUSES. The mode of action of the avian myeloblastosis P32 protein with endonuclease activity will represent a major area of interest. A long range objective will be to elucidate the role of this protein in retrovirus replication. Interrelationships between the Moloney murine leukemia virus RNase H-I and -III will be further established, and the possible role of RNase H in proviral DNA integration analyzed. DNA VIRUSES AND HUMAN CANCER. Major emphasis will be on the molecular characterization of the clone genomes of JC virus and human papillomavirus (HPV) types 1 to 4, the cloning of HPV-5, and the analysis of cancer for viral sequences using these cloned prlbes. Studies will be completed analyzing human cancer tissues not yet screened for nucleic acid sequences of groups A to E human adenoviruses and BK virus.